ColumnsDrug-Drug Interactions (DDIs) in Psychiatric Practice, Part 5: Major Types of Pharmacodynamic DDIs Based on Mechanism of Action (With Updated Neuroscience-based Nomenclature)PRESKORN, SHELDON H. MD; GERMANN, ALEXANDERAuthor Information PRESKORN and GERMANN: Kansas University School of Medicine-Wichita, Wichita, KS The column has been adapted with updates conforming to Neuroscience-based Nomenclature with permission from table 3 in Preskorn’s Drug-Drug Interactions With an Emphasis on Psychiatric Medications, First Edition, West Islip, NY and Durant, OK: Professional Communications; 2018. To order a copy of the book, readers can call 1-800-337-9838 or visit the Professional Communications website at www.pcibooks.com. Over his 40-year career, S.H.P. has worked with over 139 pharmaceutical and biotech companies in the United States and throughout the world. Over the past year, he has received grants/research support from or has served as a consultant, on the advisory board, or on the speaker’s bureau for Alkermes, Allergan, Bionomics, BioXcel, Janssen, National Institute of Mental Health, Perception Neuroscience, and Sunovion. All clinical trial and study contracts were with and payments made to the Kansas University Medical Center Research Institute, a research institute affiliated with Kansas University School of Medicine-Wichita. A.G. declares no conflicts of interest. Please send correspondence to: Sheldon H. Preskorn, MD, Kansas University School of Medicine-Wichita, 1010 N. Kansas, Wichita, KS 67214. Journal of Psychiatric Practice: May 2019 - Volume 25 - Issue 3 - p 206-211 doi: 10.1097/PRA.0000000000000386 Buy Metrics Abstract This column is the fifth in a series exploring drug-drug interactions (DDIs) with a special emphasis on psychiatric medications. In the preceding column, a classificatory system based on mechanism of action was presented and a table was provided outlining the primary, known mechanism(s) of action of all commonly used psychiatric medications. This column presents a parallel table summarizing major types of pharmacodynamic DDIs based on mechanism of action. Clinicians can use these 2 tables to predict pharmacodynamically mediated DDIs. As discussed in the third column in this series, a classification scheme for drugs based on what enzymes, if any, are responsible for their biotransformation as a necessary step in their eventual elimination and whether a drug is an inhibitor or inducer of those enzymes can be used to predict pharmacokinetic DDIs mediated by cytochrome P450 enzymes, just as the mechanism-based classification system presented in this and the fourth column in this series can be used to predict pharmacodynamic-based DDIs. The ultimate intent of this series is to present a simple way of conceptualizing neuropsychiatric medications in terms of their pharmacodynamics and pharmacokinetics to allow prescribers to take these facts into consideration when they need to use >1 drug in combination to optimally treat a patient. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.